Method of cleaning boilers



June 3.0, 1931.

B. M. THOMPSON 'umuon OF cnmnme 'BOILERS/ Filed June 24. 1927 5Sheets-Sheet '1 flee-fab M Thompson.

INVENTOR v BYMQ ATTORNEY June 30, 1931. .B. M. THOMPSON 1,812,275

. METHOD OF CLEANING BOILERS Filed June 24, 1927 3 Sheets-Sheet 2INVENTOR ATTORNEY June 30, 1931. B. M. THOMPSON METHOD OF CLEANINGBOILERS Filed June 24, 1 927 3 Sheets-Sheet 5 Ber/0h /1. Thompson.

INVENTOR ATTORNEY Patented Jaa ao', 1 931 p BEBIAE I. THOMPSON, FCHEYENNE, WYOMING METHOD or oLEANmoBomEns Application 111m June .24,1927. Serial No. 501,268.

(GRAlTTED UNDER THE ACT OF MARCH 3, 1883, AS AMENDED'AI'RIL 30, 1928;370 0. G. 757) My invention relates broadly to methods of i cleaningboilers ,of stationary or moving 6 sumed by the present methods ofcleaning boilers and prevent any director indirect. injury thereto, andthe frequent use of which will increase. the efliciency and prolong theuseful life of the boiler. With'the methods now in use it has beennecessary to remove the side casings of the boilers, thesoot cleaningdoors and baflles, butwith my invention no part of the boiler need beremoved. The

usual prior method is to manually clean away the soot and solidcombustion deposit, that has collected to a thickness of from two to sixand more inches ar'oundthe-external surfaces of the lower 'drum of theboiler and between, above and below, the tubes, b means of a brush orother instrument. '1 is method is not only expensive but usuallyconsumes several weeks for a complete cleaning of a boiler.

5 But with my methodone man and one apparatus for the practice of saidmethod may clean such boiler'in a day, or two men and two suchapparatus, one for each nest of tubes, may accomplish this work in halfa day, far better than the same may be otherwise done. Furthermore, fromthe natural construction of the boiler, it is practically im-- possible.to reach every point around the pipesand clean the combustion deposittherefrom by any manual means heretofore em plo ed 40 Sleam orcompressed a1r, with or without sand, 'will not efiiciently remove said'com bustion deposit; while such sand blast in the hands of other thanthe most skilled operator is quite likely to unduly wear, or cutthrough,

4 the boiler 7 tubes, especially where said deposit is of variablethickness, as it usually is, and the difiiculty of distinguishing, underordinary working conditions, when saiddeposit has been cut'through atany place and wltign such sand is cutting into any boiler tu vHeretofore the custom has always been to keep liquids away from thecombustion chambers ofboilers and the parts thereof exposed in suchchamber. Such custom obviated liquids injuring and disintegrating therefractory linings of such chambers, as well as corrosion, pitting,deterioration and shortening of the life of the boiler and its metallicparts occasioned heretofore by acid or other formar tions caused by thereaction of said liquid, even though it be water, upon said deposit; butin spite of saidlong custom I have discovered that liquid may be so usedwithout harmful result, and that my methodremoves said deposit beforeany such injurious reaction may occur, as well as washes the surfacesfrom which it removes said deposit to insure that no harmful results mayoccur.

I have likewise discovered that the constituents of said combustiondeposit vary with content of water soluble constituents varying fromabout 3 per cent to about 20 per cent of the mass. All of theconstituents that I have found in said deposits are finely divided andintimately commingl-ed in the mass;

Other samples may vary further and include other substances ;andallcontain more or less sulphur and other substances which set up strongreactions, very injurious v to i the area and rate of said absorption;that metal, when associated with water or other like liquid, and whichsubstances are classed above as water soluble.

As a part of or contributing to my invention I have likewise discoveredthat by creatsaid external stress; that liquid may be applied to saiddeposit so as to create each of the aforesaid stresses; that when liquidis so applied to said deposit its water soluble constituents in theaffected area of said deposit are quickly liquefied and washed outforming a multiplicity of interstices in said area of deposit; that saidevacuated interstices form channels for the entrance, and quicktransmission of the effects, of said liquid to a, substantial depththroughout said affected area of said deposit; that one of the effectsof liquid upon said mass is that its water-absorbent constituents absorbsaid liquid; that said evacuated interstices increase said absorptionexpands the water-absorbent constituents of said mass that saidexpansion sets up internal stresses in said affected area of said mass;that part of said mass is relatively brittle and non-elastic; that saidinternal stresses may substantially fracture some samples of said massin the area kept supplied, by said evacuated interstices and otherwise,with said liquid for a sufficiently long period, but that when saidaffected area is subjected to the external impact of the liquid itsfracture is thereby facilitated, as well as assured even when said mass,in whole or in part, may be of such character as may not be ultimatelyfractured by saidinternal stresses.

I have further discovered that said external stress on said deposit,through the channels of said evacuated liquid filled interstices,transmits said external stress in part to the interior of said mass,where the force of said impacted liquid suddenly accelerates the rate ofabsorption of the water-absorbent constituents of said mass and therebysubstantially increases their expansive stress upon said mass affected;that said impacted liquid also imparts its stress to the non-absorbentconstituents of said affected mass and thereby, and otherwise,substantially augments the internal stresses to which said affected areaof the mass was subjected before the application of said externalstress; that said internally transmitted part of said external stress isusually the first supplement to be applied to said initial internalstress, and the same continues as long as said external impactcontinues, while said further supplemental internal stress due to saidfurther expansion is the culminating internal stress, that saidculmination and said other internal stresses are continued as long assaid external stress is applied; that said stresses thus applied, andcontinued to the extent necessary, readily, quickly and eificientlyfracture into relatively small particles that are incapable of beingretained upon the round as well as-ang'ular surfaces upon which theywere deposited, and which may be readily conveyed by the spent liquid toa collecting point and thence transmitted even by a hose to a place ofdisposal, all with little manual effort and substantial speed.

In former boiler. cleaning, by a blunt instrument which was frequentlyused to chipofi' said deposit, man blows were delivered upon themetallic parts of the boiler which tended to crystalize the sameandshorten the life of the boiler; but with my invention substantially novibrations are produced in the boiler parts and hence no crystallizationre sults, or is contributed to, from the use of my invention, as theimpact of the liquid produces no injurious vibrations.

In the method I have developed it is only necessary to allow the boilerto cool down and to have the fire box cleaned out when the work ofcleaning the boiler may be started.

Further objects of my invention will appear more fully hereinafter asthe description of the method is developed.

My invention consists substantially in the method and the various stepsassociated therewith as will be more fully hereinafter set forth, andfinally pointed out in the appended claims.

Reference is to be had to the accompanying drawings forming a part ofthis specification in which like reference characters indicatecorresponding parts throughout the several views and in which:

Figure 1 is a View of one of the many types of apparatus by which mymethod may be applied to an inverted V-type boiler, which 1s shownpartially in section, the right hand nest of tubes 3, drum 1 and wall 5being each broken away,

Figure 2 is a sectional view of a portion of the shield and the methodof mounting the trough upon the boiler,

Figure 3 is a modification thereof;

t Figure 4 is a sectional view of the packing s rip,

Figure 5 is a view of my preferred form of clamping device, v

Figure 6 is a View of thesprayer valve and nozzle,

Figures 7 8, and 9 are views of the tips of the different nozzles that Ihave used to wash the masses of combustion deposit out of the moreinaccessible places around the base of the tubes.

Referring to Figure l, numerals 1 and 2 represent a lower: and upperboiler drum respectively of an inverted V-type water-tube boiler thatare connected together by the 5 usual tubes 3. The boiler has beenshowmm cleaned by scrubbing with steel wool or a wire brush until thereis a clean surface along the drum between the tubes and the firebrick.

A large canvas shield is then hung from a point near the upper ends ofthe tubes '3 and secured at the lower end to the boiler along and uponthe polished strip in a manner to be hereinafter described, so that allassociat-.

ed parts of said boiler above said strip be come, during the cleaningoperation, a part of saidshield. V v

Referring to Figure 2, numeral 6 represents a canvas trough thatconstitutes the lower portion of the canvas shield above referred to.The lower edge of the canvas shield is clamped within a packing member 7shown in detail in F' 4. TlllS packing member is placed along the cleanstrip between the boiler and the firebox and is held rigidly in positionby means of clamp 7a shown in detail in Fi 5.

At the lower portion of. the canvas trough are a plurality of outlettubes 8 that carry,

away the used water and waste material constituting the cleanings fromthe boiler. The tube or tubes 8 that are unattached to the run-ofi pipeor pipes, that pass through door 4, are plugged as shown at the-left ofFigure 1. Referring particularly to Figure 3, I have shown a metaltrough 9 to which the canvas shield is secured in any manner. suflicientto insure a water tight connection between the trough and the shield.Upon this trough is mounted a packin strip similar to that to bedescribed with re erence to Figure 4. The mounting -is practicallyidentical with that of thetrough shown in Figure 2; g 7

Referring particularly to Figure 4, the

- packing member consists of a plurality of U-strips 10 between which isclamped one edge of the metal or canvas trough 11 which is firmly heldin position by means of bolts 12. Within the channel of the outerUmember is a flexible acking strip 13 of rubber or like material. t willthus be seen that when any pressure is exerted against the boiler by theacking member a water tight connec $101118 obtained,

It isto be understood that any clampingnieans that will secure a watertight connection between the packing strip and the boiler is sufiicient.However, I have found that each clamp there is initially pivot 10. Itwill thus be seen that the with the types of boilers u on which myinvention has been tried, a exibly adaptable clamp of the form shownin-Fig'ure 5 iseasily adaptable'to the -varying slopes between the tubesand the boiler lower drums, as well as to the warping tendency of saidtubes due to the. high heat and Internal pressure to .which they aresubjected.

The clamp consists of two elements 15 and 16, having semicirculargrooves near the outer end and adapted to fit varying sizes of tubes.Between the straight ortion of ally mounted a threaded member 17 thatcarries a threaded screw 18' in its lower end. When the clampingelements, are placed around the tubes 3 said pendent members 17 may eachbe advantageously radially positioned about their pivotal connections toeach of their-respective clamping elements 15 and 16 to properlyposition their re ctive screws 18 to most efliciently engage t echannels-of U- I I member 10 whereby said screws 18 may, when tightenedagainst member-10,- retain the adjacent edge of shield 6. Theosition andseveral clamping units may thenbe rigidly clamped in position by meansof bolts'p'assed through the holes 19 and 20. Thetip of each screw 18when placed in the channel of the U member 10 shown in Figure 2, maythereby secure in position the removable shield 6 even when some of thescrews 18 inadvertently do not press against the Web of said U- member10; but in such contingency the rigidity of member 10, between thescrews 18 thatdo bind against saidweb, will still exertsufiicient-tension upon the rubber strip 13 to form a water-tight unionbetweenit and said a cleaned surface of drum 1 even at 1 points where ascrew 18 inadvertently should not be exerting tension against the web ofmember acking 13 may be pressed thus and thereby orma water-tighttemporary union with and throughout the length of said cleaned surfaceof the wall of the boiler drum by advancing the bolt 18 through themember 17 of each clamping unit;

The water deposited scale formed upon the wholly different nature andcharacter than the combustion deposit formed. upon the. ex-

terior surface of said tubes, and other parts of the boiler, which myinvention is especially adapted to remove rapidly-and efliciently. v

Said'combustion deposit is far less conductive of heat than the metalforming the sur faces upon which it is deposited, which requires thefrequent removal of said deposit to obtain the maximum efficiencyessential under the high fuel, labor and apparatus costs.

moves such deposit without injury to, or

impairment of, the boiler parts; the short interior surface of'suchboiler tubes. is of a i time during which the boiler need be out ofcommission for such cleaning; and the lesser cleaning cost and longerlife of the boiler being substantially less than the higher fuel costof, and liabilitydue to, ineflicient operation of the boiler; jointlyand severally invite the frequent cleaning of the boiler with myinvention.

Liquid at atmospheric temperature, applied as aforesaid, will accomplishthe re moval of said deposit/in time, but by increasing said temperaturesubstantially above atmospheric temperature the rate of said removal ofsaid deposit is substantially increased.

In the practice of my invention it has been found that water heated to atemperature of about 190 degrees and placed under a pressure of about 80pounds per square inch gives satisfactory results when employed with mymethod which is very quick, efficient and harmless when no water isapplied to the refractory linings which are usually in the form offire-brick work and indurated plastic work which are readilydeteriorated thereby. Such work, when wet, requires long periods of theapplication of a moderate continuous heat to dry out before the same canbe efficiently used; and if wet by the waste water, which usuallycontain sulphurous and other acids, said drying out leaves said acideffects. For this purpose I supply the hot fresh water through aflexible pipe 21 that is led through the access door 4 and terminates/ina sprayer 22. Attached to the sprayer is a nozzle 23 that may have thevarious tips shown in Figures 6 to 9 to direct the liquid into the moreinaccessible places about the tubes.

The liquid is applied by hose 21 to the deposit to be removed, as largean area thereof as may be desired being wetted, considering that theremoval by impact of said liquid will cause surplus and splashed liquidto keep adjacent areas of said depositwell wetted. This liquefies thewater-soluble constituents of said deposit, as well as causes theabsorption and expansion of the water-absorbent constituents of saiddeposit, and said expansion to create internal stresses in the affectedareas of said deposit. The application of further water, usually surplusor splashed liquid, will wash said liquefied constituents of saiddeposit out of the interstices where they were liquefied and keeps saidinterstices filled with cleaner liquid which is more readily absorbed bythe water-absorbent constituents of said deposit as said cleaner liquiddoes not tend as much toward stoppage of the pores of saidwater-absorbent constituents of said deposit.

Where said deposit fills the horizontal and vertical spaces between thetubes 3, as it usually does for substantial areas above drum 1, thenozzle having the opening at .its tip may be manually pressed at adownward angle against the adjacent face of said deposit whereby theheretofore described actions and reactions of absorption, liquefying,washing out, expansion, fracture and washing out of said deposit in alimited area adjacent the tip of said nozzle by the impact ofthe liquidit discharges in the direction of its longitudinal axis, and wherebysaid nozzle will be quickly imbedded, to the extent of its length, intosaid deposit with relatively slight manual pressure. By rotating saidflat nozzle about half of a turn throughout said operation the area ofeach hole will be increased. Thereupon, said nozzle may be withdrawn andother holes successively likewise formed until the face of said depositis honey-combed with such holes, which are formed therein a distanceapart dependent upon the apparent absorbent character of said deposit.While adjacent holes are being formed some of the liquid dischargedtherefrom is replacing to some extent the liquid left in adjacent formedholes, said replacement being cleaner and more readily absorbent liquid.

While said deposit is being thus honeycombed the liquid in the formedholes is being absorbed by the liquid absorbent constituents of saiddeposit in an area surrounding each hole, said absorption being directlyas well as through the interstices evacuated by the liquefiedconstituents of said deposit in said area. Said absorption causesexpansion of said liquid absorbent constituents .of said deposit andinternal stresses in said affected area of said deposit.

When said face of said deposit, or any desirable area thereof, has beenso honeycombed, a nozzle, preferably with lateral openings either 25, 26or 27, is then successively inserted into such formed holes, preferablyin the order of their formation, and rotated back and forth about a halfturn throughout said insertion and removal, whereby the laterallyimpacted preferably hot liquid will rapidly complete the disruptiveaction, initiated by said expansion, and wash out the fragments of saiddeposit in said affected area progressively as said nozzle is so movedthroughout the extent of each of said holes. I have found that a nozzlewith an opening only at its, point will accomplish this work, but itrequires a longer time, and the holes must be spaced closer together.

Some of the impacted liquid will be projected above the upper layer oftubes 3 and onto shield 30 when said nozzle breaks through the uppersurface of said deposit; as well as when moistening, and then impact ingwater upon, the deposit upon said upper layer of tubes 3. Such liquid asis not absorbed by said deposit on shield 30 will drain down saidshield. Said liquid not absorbed by said deposit on tubes 3 will. draindcwn the upper surface thereof forming pools in the depressions therein.Such drained liq- 'said deposit, in a layer thinning toward,

and in spots near, its top, causing said shield 30, over each .nest' oftubes 3 to become overheated in the areas occupied by said deposit. Suchoverheating tends to weaken and buckle shield 30, as well as to igniteany'oil that may drip, or dustthat may collect, upon theierteriorsurface thereof, and to thus enif turean danger the vessel or structurecontaining such boiler. Said tendencies are obviated by the removal ofsaid deposit atfrequent intervals, which removal in invention also mosteconomically and e ciently accomplishes concurrently with the removal ofsaid deposit from each of the nests of tubes 3. y

In m invention said shield not only causes t e impacted liquid from saidnozzle,

n'ecessa to moisten, wash out, expand,'fracwash 'ofi said daposittherefrom, to

be drained, with :the slu onto the lower portions of the shield whiclr-Iform of a part of water drum 1, and the supplemental I -.per

' functions as the temporary shield 6 which I attach thereto but. saidshield 30 serves .the further function of catching and draining,ultimately into said shield 6, said liquid accidentally as wella'snecessarily proj V above the uplayer of each tube nest 3 in theoperatlon of cleaning the boiler. I 7

It is therefore .a parent that said shield 6 exible supplemental and J--tem orary removable lower portion of, and is 0 smaller area than,the'much greater area of shield afl'orded in my invention by thepermanent shield 30, removable shield 6 and the surface of drum 1between the adjacent 1 edges of said shields 6 and 30; and that myinvention causes andrequires said shield 30 and said surface of drum 1-to seryethe aforesaid additional functions foreign to their normaluses, and in violation of the heretofore 'revailmg custom of'keepingliquid from t e fireside of boilers with their usual refractory materialand the metal arts which are usually pitted, corroded an deterioratedheretofore by acid reactions caused by the wetting of combustiondeposits thereon.

Thus in my invention, inadvertent or accidenta diversion of the liquidimpacting possible dischar ables a spareboiler to be cleaned whilethe'nozzle occasions no. injury to the refractory linings, when present, assaid members 30, 1 and 6 function together as a shield of such ample"proportions'as to catch practically all of said nozzle. This envessel isat sea, or even during a storm, without wetting or the refractory finingby such moisture. By its flexible construction said shield also preventsinjury to said refractory material in placing-or removing said shield 6,which also prevents in ury to the operator or o raters who may be thrownofi their balance lfy the motion of the and against shield 6 and itsedges.

The nozzle may be moved closer ferent shapes as well as characters ofsaid deposit, and, when the most eflicient distance or angle of impactisnot apparent to the op- ,erator'from initial inspectlon, the operatorsobservance of theefi'ectof the impact on a given area will enable him tochange the distance or angle of impact, when required, to

obtain the quicker fracture 'of said deposit.

vessel 'to, or fartherfrom, as well as'atany angle to,saiddeposit toobtain the best results with dif- When continuous impact upon one areadoes not readily produce fractureof the thus im- 'pacted area theoperator should change said lmpact to successive impacts upon sald andsome other area of said deposit, and each of said successive impactsupon the same area may beat a different angle or distance, as suchsuccessive impact stresses .will more readily fracture certaincharacters of sucli deposit. Also, some areas. of such deposit willrmgleire, for quickest fracture that each impact commenced at onedistance or 1e and continued at progressively different stancw orangles.

The liquid deflected from'other impacts usually furnishes ample washingof the surfaces from which said deposit as been removed, but when it isobserved that'any such surface is insufliciently washed it may then beimpacted and washed directly by said nozzle' discharge.

It will also belnoted that in my invention one of the fundamentalpurposes is to apply and impact the liquid in whole, or in substantialpart, from such direction that the deposit, to which said liquid to beapplied and impacted, lies between the applying and impacting nozzle andone of the shield rtions 1 and 30 so that such, or like, flir ed.inetallic parts of the boiler as thus receive :Sflld hqmd will not beinjured thereby, and whereby the parts liable to such injury orimpairment need receive 'none of said liquid; and that said flexibleremovable shield 6, or its eqgizalenhgay recggle only the dram' tietere.man racti nonecessa"- met or deflected ry any splashing of sailiquid from said shield 6 onto the refractory lining.

1m acted liquid, to avoid- Practically every different design of boilerwill require a different apparatus in order to carry out my invention inits cleaning. It was necessary to overcome existing long establishedcustom and prejudice against the use of liquid on the fire-side ofboilers, and to develop my method of cleaning the same independent ofany type of apparatus for its execution.

The nozzle shown in Figure 6 is that of the diamond type 24 that is usedfor all direct work. The nozzle shown in Figure 7 has the diamond typepoint 2a with a plurality of side slots 25 directing the liquid from thesides of the nozzle.

The nozzle shown in Figure 8 is similar to the one shown in Figure 6except that one of the sides of the diamond point is sheared off on oneside, as at 26, to direct the flow of liquid to one side. Also in thesides of the nozzle tube are a plurality of holes 27 that serve the samepurpose as the side slots shown in Figure 7. The nozzle shown in Figure9 is open ended and is used for direct washing of the larger surfacesbetween the boiler tubes.

Each of the nozzles is formed of tubing,

4 the sides of which are flattened throughout the major portion of itslength, as shown in Figure 6, in order to readily introduce the nozzle,to the extent of its flattened length, into the horizontal as well asvertical spaces between the tubes 3 of each tube nest, as well as toobtain a greater volume of liquid flowing at high velocity in aflattened stream than would be obtainable from a round nozzle of a sizereadily introducable into said spaces.

Said flat stream of liquid, ejected by said flat nozzle, may be sprayedover a. given area quicker, when the long axis of said stream issubstantially parallel with the surface to be wetted thereby, than by around stream,

of said limited size, while its greater volume of discharge of impactliquid substantially lessens the time in which said deposit may bemoistened, liquefied in part and washed out, absorb, expand, disruptedand washed away by said impacted liquid.

Said combustible deposit soon forms in constant use of the boiler and inthicknesses varying from two to more than six inches, especially overthe drums 1 and lower part of each nest of tubes 3, where, before myinvention about ninety per cent of the failure of such tubes occurred. a

The speed and ease with which my invention cleans a boiler invites itsfrequent use and which prolongs the efficient life of such boilers fromone to two years longer tha when my invention is not used.

The method that I have found most efficient is to allow the boilers tocool and have the fire removed from the fire box. As soon as thetemperature of the fire box has lowered sufiiciently to permit anoperator to work therein, the shield and trough are inserted through theaccess door. A strip is then cleaned along the lower drum 1 of theboiler just above the sloping top of the fire-brick wall 5 and below-thetubes 3; and the trough is mounted, with one edge in contact with saidcleaned strip, in the manner above described forming a water tightconnection between the boiler and the packing member. The shield is thenhungfrom the upper ends of the tubes.

After the shield and the trough have been secured in position and theliquid or water conduit is led through the access door. The operatorthen works from above the shield and inserts the nozzle between thetubes and turns on the water. Beginning near the top of each tube hefollows the spaces between the tubes down to a point in close proximityto the lower boiler drum 1. By the use of this hot fresh water, I havefound that the deposits that collect upon the tubes and moreparticularly that which solidifies into a compact mass near the base ofthe tubes of the boiler 1 is disintegrated to a suflicient fineness tobe carried from around and between the tubes into a trough and throughthe outlet conduits.

I have tried many kinds of shields,-but said flexible lower removableshield 6 has been found most efiicient, enables the operative or oeratives to work expeditiously and with sa ety in the close quarterswhere the same must be used, and especially when, to expedite the work,a separate shield 6 and one or more additional operatives aresimultaneously employed for each nest of tubes 3, wherein, as well as inthe use of but one shield,

such flexible shield 6 yields readily to, and

may be displaced conveniently by, the bodies of the operatives at pointswhere the same is not then being used as a liquid and sludge shield.Said temporary displacements of said shields 6 afford ample workingspace for the operatives and the nozzles and their hose, besidesaffording as safe gangway for the operatives substantially the wholearea between the upwardly-converging water-tubes 3, and contact withsaid flexible shields 6 affords the operators timely warning that hardersubstances are being approached.

An unflexible and unyielding shield 6 could not be employed withoutsacrificing 'the' aforesaid advantages, and must be made in smallsections, to get them into and out of time.

By this method it will be seen that by applying hot water under pressurein the manner above described that sections of a boiler may bethoroughly cleaned-in an operation that consumes very little timeincomparison with that necessary for cleaning'thesame boiler by themethods and apparat'us'heretofore used. This substantial saving of timeY that a boiler must be out of commission while being cleaned is ofmaterial commercial value, and in war time said value is accentuated.The facility with which my invention enables a spare boiler to becleaned whileits vesselv is in operation, even in a storm, furtherenhances-its advantages.

It will be'understoodthat the above descri tion andaccompanying drawingscompre 'end only the general and preferred em- 'bodiment' of myinvention and that minor de- 201,267, I c aim theapparatus herein dis-vtail changes'in the steps of the method or their sequence may be madewithin the scope of the appended claims without sacrificing any of theadvantages of my invention.-

In my 00- nding application, Serial No.

closed by'which may be practiced the method herein claimed. v. v

The invention herein described may be manufactured and used by or forthe Government of the United States for governmental pur' oses withoutthe payment tome of any.roya ty thereon or therefor.

Having thus described my invention what I claim is as follows: v 1. Themethod of cleaning boiler tubes which includes the steps of washing thesolid deposits therefrom by impacting a heated li uid thereon at anangle and preventing said liquid from contacting parts that might bedamaged'thereby.

2. The method of cleaning boiler tubes which includes the steps ofwashing the solid deposits therefrom by means of a heated solvent liquidunder pressure impactin thereon in a volume sufiicient to accomp ish theremoval of the deposits without forming harmful reactions between saiddeposit and liquid, and preventing the washingeliquid from contactingparts that might aged thereby.

3. In the operation of cleaningthe combustion deposit from boiler parts,the method 'includingrthelfollowing steps introducmg liquid underpressureinto thefire-sideof a boiler. applying said liquid to saiddeposit and obtaining a reaction therefrom, impacting further liquidupon portions of the deposit to which liquid had been applied, andpreventing the liquid from contacting parts that might bedamaged'thereby.

4. In the operation of cleaning the combustion'deposit from boilerparts, the method including the following ste, s; introducing 1i uidunder pressure intoit e fire-side of a bo1ler, applying said liquidsuccessively to relatively small areas of said surfaces to be cleaned,and keeping said liquidfrom contact aged thereby.

dam-

with such associated partsas may injured in the method thereofconsistingof expandingfthe expansible constituents of said de-. v

posit and keeping the expanding agency fromcontacting parts'that mightbe dam- '7. In the'operationof cleaning vthe combustion deposit fromboilerparts, the steps in the method thereof consisting of expanding theexpansible constituents ofzsaid deposit successively in relatively small'areasof said deposit, successively impacting-said expanded areas, andkeeping the expanding and impacting-agencies from contact withtheassociate'd portions of the boiler liable to be injured thereby.

8. In. the operati the method'thereof consisting of creating an internalstress in sai d deposit. subjecting the stressed deposit to anexternalstress by substantially impacting the same with a. ;]'etof themedium creating said internal stress, and maintaining said medium out ofcontact vwith other parts of the boiler liableto be impaired thereby,

9. In the operation of cleaning the combustion deposit from boiler,parts, the step.

in the method thereof consisting of successively creating an'internalstress in said deposit, successively subjecting the stressed deposit toexternal stresses, and keeping thestressing agency from contact withassociated portions ofthe' boiler liable to be injured thereby.

10. In the operation of cleaning the combustion'deposit from boilerparts. the steps in the method-thereof consisting of applying liquidtoandexpanding the absorbent conon of cleaning the com-f bustion depositfrom boiler parts. the steps in stituents of said deposit,impgctingtheex panded deposit withfurther liquiduntil said 1 deposit isdisintegrated, keeping the applied and impacted spent liquid fromcontact with associatedboilernpartsliable to be injured thereby, andremoving thespent liquidand sludge from the boiler. p.

.11. In the operation of'cleaning the combustion deposit from boilerparts, the steps in the method thereof consisting of manually cleaning apart of the boiler below-parts to be cleaned, applying a liquid shieldto said part, and applying liquid to said parts to be cleaned.

12. In the operation of cleaning the combustion deposit from boilerparts, the steps in the methodthereof consisting of applying a liquidshield below parts to be cleaned,- applying liquid under pressure to thedeposit to be cleaned from such direction that said deposit lies betweenthe liquid to be applied and said shield, whereby said shield mayreceive substantiall no direct application of said pressure liquid?BERIAH M. THOMPSON.

